Harden admin login: RBAC-safe controls, 2FA, bot-scoring, rate limits (#9)

Adds a layered set of protections around the admin login and the app edge.

Trust proxy (server/src/utils/trustProxy.js)
- Configurable via TRUST_PROXY; pin to the newt agent ("ptero") LAN IP so
  X-Forwarded-For is trusted ONLY from that peer. A blanket "true" is
  rejected (coerced to 1) to prevent XFF spoofing that would dodge every
  IP-based control. DEBUG_TRUST_PROXY logs peer/XFF/req.ip to re-verify the
  proxy IP without a redeploy. Documents the Omada static-reservation
  assumption.

Login throttling (server/src/middleware/loginProtection.js, rateLimit.js)
- express-slow-down progressive delay + the existing hard rate cap + a
  separate per-IP exponential backoff that persists across the rate window.
  All failures return one generic message (no user/pass disclosure).

Honeypot (login form + auth.controller)
- Hidden, plausibly-named field ("company"); a filled value fails
  generically and is scored as an unambiguous bot.

Optional per-user TOTP 2FA (speakeasy/qrcode)
- totp_secret/totp_enabled columns (+ idempotent migration). Self-service
  Account page: enroll via QR, confirm a code to enable, code-gated disable.
- Login is two-step for enrolled users: after the password, a short-lived
  signed challenge (stage:'totp', not a session) is required before the
  real session is issued.

Bot / scanner scoring + IP ban (server/src/middleware/botScore.js)
- Weighted CMS-scanner paths (this app uses none). Junk paths 404 FIRST,
  unconditionally — independent of score/ban state, so a scanner rotating
  through fresh Cloudflare IPs gets no free pass. /wp-admin/install.php is
  the top-weighted near-1-hit ban (worst offender in prod logs). Per-IP
  score with quiet-period decay temp-bans an IP from ALL routes once past a
  (deliberately low) threshold, to protect /admin from credential stuffing.
  Failed logins and honeypot hits feed the same score.
- Periodic sweep evicts stale, unbanned, quiet entries so the in-memory
  store can't grow unbounded; the interval is unref'd and cleared on
  graceful shutdown.

Tests: node --test suite (40) covering trust-proxy parsing + live req.ip
(incl. pinned-IP), rate limiter + exponential backoff, honeypot rejection,
TOTP verify (enabled/disabled) + challenge-isn't-a-session, bot-score
threshold/decay/ban + junk-404-independence + install.php + store sweep.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

server/src/utils/trustProxy.js

@@ -0,0 +1,102 @@
+// ── Trust proxy configuration ──────────────────────────────────────────────
+//
+// Real request path for this deployment:
+//
+//     client → Pangolin → newt tunnel agent ("ptero", separate VM)
+//            → this app (its own VM), over the LAN
+//
+// The hop that actually opens the TCP connection to this app is ptero, so from
+// Express's point of view ptero is THE trusted proxy and its LAN IP is the
+// right-most/most-recently-added entry to reconcile against. The real client IP
+// arrives in X-Forwarded-For. req.ip / req.secure must reflect the real client
+// because the rate limiter, exponential backoff, bot-scoring ban, and activity
+// log all key on req.ip — so this is a prerequisite for every other control.
+//
+// Recommended production value: pin TRUST_PROXY to ptero's LAN IP exactly. That
+// is stricter than a hop count: Express will only honour XFF on connections that
+// actually come from ptero, so nothing else on the LAN can inject a forwarded
+// header. See TRUST_PROXY in .env.example for how to set it.
+//
+// IMPORTANT ASSUMPTION: pinning ptero's IP assumes ptero holds a STATIC IP
+// (a DHCP reservation in Omada). If that reservation does not exist, a lease
+// change would silently move ptero to a new IP and every XFF would stop being
+// trusted — req.ip would collapse to ptero's (new) address for all clients,
+// breaking rate limiting/bans. Verify the reservation before relying on this,
+// and use DEBUG_TRUST_PROXY (below) to re-check the observed proxy IP without a
+// code redeploy if it ever needs to change.
+//
+// We deliberately DO NOT use a blanket `true`. `true` trusts every hop and takes
+// the left-most (client-supplied, spoofable) XFF entry, letting an attacker forge
+// their apparent IP to dodge rate limits / bans.
+//
+// TRUST_PROXY accepts:
+//   - unset / ''      -> 1            (single proxy hop fallback)
+//   - an integer      -> that many trusted hops (e.g. "2")
+//   - "false"         -> false        (no proxy; direct connections only)
+//   - "loopback" etc. -> the express preset string, passed through
+//   - a CSV of IPs / CIDRs -> that list (e.g. ptero's LAN IP: "10.0.0.42")
+//
+// `true` is intentionally rejected (coerced to 1) with a warning, so it can't be
+// set by accident.
+
+const log = require('./logger')('trustproxy')
+
+function truthyEnv(v) {
+  return ['1', 'true', 'yes', 'on'].includes(String(v || '').trim().toLowerCase())
+}
+
+const PRESETS = new Set(['loopback', 'linklocal', 'uniquelocal'])
+
+function parseTrustProxy(raw = process.env.TRUST_PROXY) {
+  const val = (raw == null ? '' : String(raw)).trim()
+
+  if (val === '') return 1 // default: one hop (Pangolin)
+  if (val.toLowerCase() === 'false') return false
+  if (val.toLowerCase() === 'true') {
+    log.warn('TRUST_PROXY=true is unsafe (trusts spoofable client XFF); using 1 hop instead')
+    return 1
+  }
+
+  // Pure integer → hop count.
+  if (/^\d+$/.test(val)) return Number(val)
+
+  // Single express preset keyword.
+  if (PRESETS.has(val.toLowerCase())) return val.toLowerCase()
+
+  // Otherwise treat as a comma-separated list of trusted IPs / CIDRs (and/or
+  // preset keywords), which Express accepts as an array.
+  const list = val
+    .split(',')
+    .map((s) => s.trim())
+    .filter(Boolean)
+  return list.length === 1 ? list[0] : list
+}
+
+// Apply the setting to an Express app and log what was chosen.
+function applyTrustProxy(app, raw = process.env.TRUST_PROXY) {
+  const setting = parseTrustProxy(raw)
+  app.set('trust proxy', setting)
+  log.info('trust proxy configured', { setting: Array.isArray(setting) ? setting.join(',') : setting })
+  return setting
+}
+
+// Temporary diagnostic middleware, OFF by default. Set DEBUG_TRUST_PROXY=1 to
+// log, per request, the raw peer address and forwarded header alongside the IP
+// Express resolved — so the real proxy IP (ptero) can be re-verified in-place
+// without a code change if it ever moves. Mounted before the bot guard so it
+// still fires for scanner/junk requests (whose source IPs are what we want to
+// see). Turn it back off once verified; it is noisy.
+function trustProxyDebug(req, res, next) {
+  if (truthyEnv(process.env.DEBUG_TRUST_PROXY)) {
+    log.info('trust-proxy debug', {
+      remoteAddress: req.socket && req.socket.remoteAddress,
+      xForwardedFor: req.headers['x-forwarded-for'] || null,
+      resolvedIp: req.ip,
+      method: req.method,
+      path: req.originalUrl,
+    })
+  }
+  return next()
+}
+
+module.exports = { parseTrustProxy, applyTrustProxy, trustProxyDebug }